// external.cpp -- external variables
// compile with support.cpp
#include <iostream>

using namespace std;

// external variable
double warming = 0.3;   // warming define

// function prototype
void update(double dt);

void local();

int main() {     // uses global variable
    cout << "Global warming is " << warming << " degrees.\n";
    update(0.1);    // call function to change warming
    cout << "Global warming is " << warming << " degrees.\n";
    local();            // call function with local warming
    cout << "Global warming is " << warming << " degrees.\n";
    return 0;
}
